A fiery protest raged on in the Ukrainian capital early Wednesday as a geopolitical struggle between Russia and the West turned deadly once again.

At least 25 deaths were confirmed after thousands of riot police armed with stun grenades and water cannons fought with anti-government protesters in Kiev. It was the bloodiest day since the former Soviet republic won its independence.

In the wake of deadly street clashes on Tuesday, cops charged into a large opposition camp that has been the epicenter of nearly three months of demonstrations.

The Health Ministry said 25 people had been killed in the fighting in the capital, including nine police officers.

The Interior Ministry said 351 cops had been injured, including 59 by gunfire, during the clashes. At least 221 protesters were also injured.

It was the deadliest violence in nearly three months of protests in the Ukrainian capital in a struggle over the nation’s identity and future.

"They can come in their thousands but we will not give in. We simply don't have anywhere to go. We will stay until victory," a 44-year-old from the western region of Ternopil who gave only his first name of Volodymyr told Reuters.

In the western part of Ukraine on Wednesday, anti-government protesters seized government buildings in a few cities, Reuters reported.

Police said protesters took over regional administration headquarters in Ivano-Frankivsk and Lviv. The website of a newspaper, Ukrainska Pravda, said protesters torched the main police station in Ternopil and were attempting to seize the headquarters of regional administration.

Any immediate diplomatic end to the standoff remained uncertain. Police were still seeking to dismantle the camp early Wednesday but few of the some 20,000 protesters there at left, and more were seen coming.

Opposition leader Vitaly Klitschko, former heavyweight boxing champion, said he had quit late-night talks with President Viktor Yanukovich without reaching any agreement on how to end the violence.

"This is an island of freedom and we will defend it"

Klitschko returned to the square afterward and urged the protesters to defend the camp.

"We will not go anywhere from here," Klitschko told the crowd. "This is an island of freedom and we will defend it," he said.

A report on a Ukrainian newspaper website quoted Klitschko as saying the president had demanded that the central square in Kiev occupied by anti-government protesters be unconditionally cleared.

In a statement Wednesday, President Yanukovich maintained his call for a peaceful resolution to the stand-off instead of violence.

"I am totally against a heavy-handed approach and the more so against bloodshed," Yanukovich said. "I once again call the leaders of the opposition, who claim that they aim for a peace settlement, to separate themselves from the radical forces which provoke bloodshed and clashes with law enforcement services."

Vice President Joe Biden called Yanukovich, urging him to pull back government forces and exercise maximum restraint, the White House said.

Many of the some 20,000 protesters who filled Independence Square sensing that Ukraine's political crisis was reaching a critical turning point remained defiant amid a massive fire.

Protesters shouted “Glory to Ukraine” as burning tents lit up the night sky.

Flames shot high into the air outside a ring of apparent opposition protesters in the capital as midnight struck. Men tossed what appeared to be fuel to keep the fires burning. Some explosions were heard.

Demonstrators torched vehicles and threw stones with authorities responding with rubber bullets and smoke grenades, often while singing the Ukrainian national anthem, The Associated Press reported.

From Paris, Secretary of State John Kerry issued a statement condemning the violence and urging the Ukrainian government and protesters to take steps to de-escalate the situation through dialogue.

“Rather than issuing ultimatums, the government of Ukraine should immediately resume talks with senior opposition leaders and support dialogue through Ukraine's democratic institutions, including parliament, the Rada. … ” Kerry said. “We also call on protesters to refrain from violence of any kind; Ukraine's deep divisions will not be healed by allowing more innocent blood to be spilled,” Kerry added.

The State Department also issued an alert to U.S. citizens abroad about the increased risk of travel to the Ukraine amid the unrest.

"U.S. citizens are urged to maintain a low profile and to remain indoors at night while clashes continue," the alert said.

U.N. Secretary-General Ban Ki-moon expressed shock at the escalating and "unacceptable" violence and called for "the immediate renewal of genuine dialogue leading to rapid results," U.N. spokesman Martin Nesirky said. "Preventing further instability and bloodshed is a paramount priority."

The violence flare-up comes after weeks of relative calm in the streets of Kiev.

Protests erupted on Nov. 21 when Yanukovych opted for a Russian bailout rather than a trade deal with the European Union. Protests started out largely peaceful, but have become increasingly characterized by violence between riot police and far-right groups.